There are three ways in which heat be transferred - conduction, convection, and radiation. which types of thermal transfer involves fluids of different temperatures and densities?

Convection.

Explanation:

Let us define each of the type of thermal transfer first:

- radiation is heat transfer that does not include contact between the objects. It's mediated by infra-red radiation, waves from the invisible radiation spectrum.

- conduction is heat transfer which is mediated through direct contact between objects (holding a hot cup of tea, for example)

- convection is a heat transfer found in gases and liquids. Due to different temperatures in two parts of liquid, there will also be a different density ( hotter parts have lower density). Lower density parts will start moving upwards while higher density parts, due to gravity, will move downward. As they move, they will gain or receive heat, which will cause new temperature differences and the moving will restart.

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-